(a) Field of the Invention
The present invention relates to a method and apparatus for generating frames for error correction to perform unequal error protection.
(b) Description of the Related Art
In wired or wireless transmission of multimedia data, multimedia data is compressed using a certain compression standard to reduce the amount of data, due to limited transmission capacity. In this instance, the worse the transmission channel becomes, the higher the bit error rate (BER) and the lower the picture quality or audio quality of decoded multimedia data becomes.
The bit error rate may be improved by forward error correction (FEC) in a physical layer or video layer of a transmission system. Error correction performance is determined by code rate if the length and type of a code word are constant. The lower the code rate, the higher the error correction performance.
Compressed video data has a different priority level within the same GOP (group of pictures) or picture, depending on how much an error can affect reception performance. Compressed video data may have various levels of priority for different layers (i.e., GOP layer, picture layer, slice layer, etc.).
In FEC for error protection of compressed multimedia data, the use of different code rates for each priority level is referred to as unequal error protection, and the use of the same code rate for all data regardless of priority is referred to as equal error protection (EEP).
Given the same payload rate and the same bit error rate, unequal error protection, compared with equal error protection, gives better picture quality or audio quality for decoded data. Unequal error protection uses two or more different code rates. Thus, it is difficult to maintain a constant payload rate when data length or position varies with priority.
Accordingly, in general, a transmission system requiring a constant payload rate uses equal error protection, and a transmission system using a variable payload rate uses unequal error protection. In a system that allows for constant payload rate and fixed data length or position for each priority level, either equal error protection or unequal error protection can be used, but the latter gives better performance.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.